When electrical characteristics of a target object such as a semiconductor wafer or the like are inspected by using a plurality of probes, the electrical characteristic inspection is performed by, e.g., imaging tips of the probes provided at a probe card by a camera, detecting tip positions of the probes and contacting the probes with electrode pads of the target object. When the tip positions of the probes are detected by using a camera, time is required to focus the camera on tips of the probes. As a result, considerable time is spent to align the target and the probe card. For this reason, in general, the alignment is not performed for all of the probes but performed by, e.g., selecting several representative probes.
However, in case where the electrode pads are miniaturized, the probes may not entirely contact with the respective electrode pads. Thus, it is preferable to detect the tip positions of all of the probes. Further, the probe card is not free from variations in production quality or the like, and even if the probe cards are of the same specification, the variations are hardly avoidable in the manufacturing process. This makes it necessary to detect the tips of the probes more precisely.
Moreover, various kinds of probe cards are developed by different probe card makers, so that there arises a need to develop dedicated algorithms for recognizing three-dimensional images of a plurality of probes. However, huge costs are incurred in developing such dedicated algorithms. Therefore, by transferring the probes to a two-dimensional film, the algorithms can be easily developed.
For example, Japanese Patent Laid-open Publication No. 2005-079253 discloses a method for detecting a tip status of probes by using a transfer sheet. In this method, needle traces are formed on the transfer sheet by bringing thermally expanded probes into pressure contact with a transfer sheet disposed on a support next to a mounting table. After the needle traces on the transfer sheet are detected, the alignment of the thermally expanded probes is carried out.
In the technique disclosed in Japanese Patent Laid-open Publication No. 2005-079253, the needle traces are formed on the transfer sheet to align the probes, and the formed needle traces are eliminated, for next alignment, by melting resin by heating the transfer sheet with the use of the heating unit. Since, however, the transfer sheet is made of thermoplastic resin, e.g., polyolefin-based resin or polyvinyl chloride-based resin or the like, the needle traces are not eliminated unless the transfer sheet is heated to, e.g., about 100 to 120° C., and maintained at this temperature for a specific period of time (e.g., about one minute), which decreases a throughput. Further, the transfer temperature of the transfer sheet should be adjusted to a temperature close to a room temperature. Therefore, the needle traces may be eliminated during the inspection performed at a high temperature above 100° C. Accordingly, it is difficult to use this method in the high temperature inspection. Even if this method is used, since the temperature of the transfer sheet is considerably lower than that of the mounting table, the large temperature difference between the transfer sheet and the mounting table may adversely affect the high-temperature inspection.